Air Quality at Yosemite National Park

What’s in the Air?

Yosemite NP, California

Most visitors who come to national parks expect clean air and clear views. However, Yosemite National Park (NP), California, experiences some of the worst air pollution of any national park in the U.S. The park is downwind of many air pollution sources, including agriculture, industry, major highways, and urban pollutants from as far away as the San Francisco Bay Area. Air pollutants carried into the park can harm natural and scenic resources such as forests, soils, streams, fish, and visibility.

How is air pollution affecting Yosemite National Park?

Ground-level ozone in the park often reaches levels harmful to plants; ozone levels also exceed human health standards at times. more »

Nitrogen and sulfur in air pollution are carried by rain and snow into park ecosystems causing changes to high elevation lakes and streams. more »

Airborne mercury and pesticides deposit on park lands and waters, potentially accumulating in fish to levels harmful to wildlife and human health. more »

Fine particles of air pollution, often a result of fire and smoke, cause haze in the park, affecting how well and how far visitors can see vistas and landmarks. Fine particle levels also exceed human health standards at times. more »

What is the National Park Service doing about air pollution at the park?

Working with federal, state, and local agencies, industry, and public interest groups to develop strategies to reduce air pollution and protect and restore park resources. The NPS also reviews plans for development that may increase air pollution in national parks. more »

Using an environmentally friendly alternative fuel vehicle fleet and the free Yosemite Shuttle hybrid bus system for park visitors, reducing the number of vehicles on some of the busiest roads in the park. Learn more about the steps Yosemite NP is taking as part of the Climate Friendly Parks program.

Featured Content

Pollutants including ozone, nitrogen, mercury, and fine particles affect resources such as forests, streams, and scenic vistas. Find out how on our Yosemite NP Air Pollution Impacts web page.

Studies and monitoring help the NPS understand the environmental impacts of air pollution. Access air quality data and see what is happening with Studies and Monitoring at Yosemite NP.